Effect of Acid- and Ultraviolet/Ozonolysis-Treated MWCNTs on the Electrical and Mechanical Properties of Epoxy Nanocomposites as Bipolar Plate Applications

Abu Bakar Sulong,Hendra Suherman,Nishata Royan Rajendran Royan,Jaafar Sahari

doi:10.1155/2013/717459

Abstract

Carbon nanotubes (CNTs) have a huge potential as conductive fillers in conductive polymer composites (CPCs), particularly for bipolar plate applications. These composites are prepared using singlefiller and multifiller reinforced multiwalled carbon nanotubes (MWCNTs) that have undergone a chemical functionalization process. The electrical conductivity and mechanical properties of these composites are determined and compared between the different functionalization processes. The results show that UV/O3-treated functionalization is capable of introducing carboxylic functional groups on CNTs. Acid-treated CNT composites give low electrical conductivity, compared with UV/O3-treated and As-produced CNTs. The in- and through-plane electrical conductivities and flexural strength of multifiller EP/G/MWCNTs (As-produced and UV/O3-treated) achieved the US Department of Energy targets. Acid-treated CNT composites affect the electrical conductivity and mechanical properties of the nanocomposites. These data indicate that the nanocomposites developed in this work may be alternative attributers of bipolar plate requirements.

Highlights

Bipolar plates are the key components in a proton exchange membrane fuel cell (PEMFC) and perform as current conductors between cells, provide conduits for reactant gases flow, and constitute the backbone of a power stack [1]
The in-plane electrical conductivity of polymer composites depends on the arrangement of reinforcement materials and the dispersion and distribution of the reinforcing materials in the polymer matrix
A comparison between the three types of composites shows that the composites with As-produced Multiwalled carbon nanotubes (MWCNTs) achieved the highest in-plane electrical conductivity of 2.84 S cm−1, whereas the composites with UV/O3- and acid-treated MWCNTs gave electrical conductivity values of 2.2 and 1.1 S cm−1, respectively

Summary

Introduction

Bipolar plates are the key components in a proton exchange membrane fuel cell (PEMFC) and perform as current conductors between cells, provide conduits for reactant gases flow, and constitute the backbone of a power stack [1]. Conventional pure graphite (G) bipolar plates contribute significantly to the cost and weight of PEMFC stacks. Metals, such as stainless steel and metal alloys, are not preferable because of corrosion-related issues [1, 2]. The development of lightweight, low-cost, and highly conductive polymer composite bipolar plates with a scope for mass production can aid the rapid commercialization of PEM fuel cells [3,4,5]. The reinforcing and/or electrically conducting fillers commonly used, including G, carbon fiber, and carbon black, have been reported to enhance the overall performance of composite plates formed using the conventional polymer processing technique [7,8,9,10,11,12,13]. Despite the MWCNTs’ wide range of potential applications, their use often remains problematic because

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